Monday, February 6, 2012

The GUIDE: "Whatizname's Disease"

This is the big one. I have actually put writing this segment off as long as I could due to the complexity of the subject. It will also probably take more than one post to do justice to the topic. SO, you have been warned!

In a list of top 10 questions that many Neuroscientists are asked about the brain, one of the following questions: "What is Alzheimer's Disease?" "What causes it?" and "How can we treat it?" will usually be in the top three.

Right from the top I am going to admit that I need help with this one. I know the effects, the symptoms and what happens, but there is so much more to the topic, that I need an expert resource for assistance. Fortunately, the U.S. National Institutes of Health feel the same way, so the National Library of Medicine, via its "PubMed" database, has help for you and me on the subject. So, I acknowledge considerable help from the Alzheimer's disease page of Pubmed Health (http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001767/).

I will start with my personal encounter with the disease. In 1979, I was a recent college graduate lookign to go to medical school to study Neurology or Neurosurgery. My grandmother was in her 70's and started showing signs of senile dementia. Alois Alzheimer had identified the disease process in 1906, but it wasn't until the 60's that researchers linked the Alzheimer's brain cell abnormalities to cognitive decline and memory loss. By 1979, the term "Alzheimer's Disease" was starting to be heard by the American public. My aunts immediately latched onto AD as the explanation for my grandmother's problems, but I wasn't so sure. AS understood in 1979, AD was presenile dementia, meaning it hit at a much earlier age than "normal" senility. Many of the known cases of AD at that time were in patients of age 50-70. I felt that claimed AD for my grandmother was stretching the definition, but I would certainly do some research to find out.

It turns out that I was right and wrong. My grandmother had actually suffered a "psychotic break" we didn't realize it at the time, but she had undergone a severely stressful experience that caused her to withdraw from normal social interaction, while at the same time appearing to lose the inhibitions that normally keep a person from acting on impulse. Still, over the years, as AD was better understood, and as we watched her deteriorate, it became apparent that she did indeed have a steady decline in mental abilities and memory, thus whether she had AD in 1979 was a moot point, she certainly had it in later years. Instead of going to medical school for a clinical Neuro specialty, I obtained a doctorate in Neuro research - at a medical school, so I did take many of the same classes - and I specialized in memory, which brought me face to face with Alzheimer's Disease on many occasions.

So, to finish off today's blog, I'll discuss the two main types of AD and what they are. For the next couple of blogs I'll talk about diagnosis, treatment, and the research being done on AD.

PubMed
Health. A service of the National Library of Medicine, National
Institutes of Health.
Illustration URL: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001767/figure/A000760.B8681/?report=objectonly

AD can only be accurately diagnosed by looking directly at the brain tissue and neurons. That means that autopsy is really the only way to be certain, but brain scans such as CT and MRI may show damaged areas in advanced cases. "Early Onset AD" is the "presenile" type that I was familiar with in 1979. The symptoms typically appear before age 60, it runs in families, and the course of the disease is very fast. Early onset AD often leads to death in a few years. "Late Onset AD" typically shows up after age 60, and in many ways is not very different from classical "senility." In fact, there are some who argue that all humans would get AD if they lived long enough. This form of the disease may also run in families, but the genetic component is not very clear.

Many doctors and neuroscientists view AD as a multi-step process as in the figure above. A third type of "pre-AD" called "Mild Cognitive Decline" frequently occurs as patients age and develop difficulty retrieving some memories or making certain decisions. The onset of MCI is often in the 50's prior to the age when such memory difficulties are "normal" (i.e. late 70's and older). The decline continues until a threshold is reached - at any age - and frank AD symptoms are seen, accompanied by a rapid loss of memory and cognitive ability.

Symptoms: (again I am indebted to Pubmed Health)

Dementia usually first appears as forgetfulness, then changes in emotional behavior or personality, mild aphasia, changes in perception, then impairment of thinking and judgment. The precursor stage - MCI - appears with the difficulty in doing more than one task at a time, inability to tune out distractions, difficulty solving problems, forgetting recent events or conversation, and constantly restarting or taking longer to complete difficult activities. AD itself is characterized as difficulty learning new tasks or performing old tasks that used to be easy, getting lost in familiar places, extreme aphasia and difficulty with language or understanding, mood changes and loss of interest, loss of social skills. As AD gets worse, these symptoms impair the ability to take care of one's self, result in inappropriate actions, depression, irrationality, hallucination, and eventually loss of memory, inability to speak or understand speech, inability to recognize family members, loss of control of bodily functions.

Alzheimer's disease is a sad, heartbreaking condition for families, and it is not a matter to be taken lightly, hence my reluctance to cover the subject until now.

I'll be back over the next few blogs to discuss more of the brain science behind AD and to give some hope for future scientific developments in this field.